I am not quite sure what triggered this memory, but I thought I'd share it with you today because it's kind of awesome.
My junior year of high school I was 16 or 17 and Sam was 4. My mother was away for the evening at some nursing related activity. Sam had been playing in the other room. Eric was over visiting me. Dad and Ben were variously occupied around the house when Sam approached holding out what appeared to be a half rotten molar. He said, "I lost a tooth." We all inspected it in horror. How had he managed to have a tooth rot and fall out, my family is kind of serious about clean teeth? We couldn't wrap our minds around it so we did what seemed natural, we put the tooth in a glass of water and waited for my mom to make sense of it.
When she came home she didn't have a chance to look at it until after Sam was in bed. After a brief moment she deduced that it wasn't a tooth at all, but rather it was a chunk of walnut. She concluded that it must have been stuck in Sam's tooth and when he dislodged it he simply thought he'd lost a tooth.
She put some change under his pillow because he'd gone to bed hopeful for the payoff (we never believed in the tooth fairy, but we knew that a lost tooth meant our parents would put some money under our pillow). She planned to explain the whole thing to Sam in the morning.
When it was explained it him that he hadn't lost a tooth he just kind of smiled. Turns out the little evil genius had just concocted the whole story when he realized that a walnut looked kind of tooth like. He had just conned the whole family.